Isoelectric Segments Research Articles

Cavotricuspid-Dependent Atrial Flutter in Patients With Prior Atriotomy: 12-Lead ECG Interpretation and Electroanatomical Characteristics.

The aim of this study was to describe the electrocardiogram (ECG) morphology and electroanatomical characteristics of counterclockwise tricuspid annular atrial flutter (CCWTA-AFL) in the patients with prior atriotomy. This retrospective study included 34 patients with CCWTA-AFL after cardiac surgery and 20 patients with typical CCWTA-AFL without prior surgery. For patients in the postsurgical group, 19 had single-loop CCWTA-AFL and 15 had a double loop CCWTA-AFL. For single loop CCWTA-AFL the F-wave in lead I was very flat in l7 of 19 patients. The F-wave morphology in the inferior leads and V1 were found to be similar to typical AFL in 14 of 19 patients. For double loop CCWTA-AFL, F-waves were positive in lead I in 13 out of 15 patients. A long isoelectric activation was measured between F-waves in most of the patients. The presence of isoelectric segments between F-waves suggested a double loop AFL, which had a sensitivity of 86.7% and a specificity of 100%. Moreover, flat F-waves in lead I suggested a single loop AFL, which had a sensitivity of 89.5% and specificity of 86.7%. All patients in the group without prior cardiac surgery had typical ECGs features of CCWTA-AFL. None of the patients showed isoelectric segments between F-waves in the inferior leads. The amplitudes of most of the leads were higher than those for single loop CCWTA-AFL in patients with prior surgery.

Characteristics of diastolic function of healthy subjects analyzed by microvoltage variability of isoelectric segments, recorded by three-axial high resolution electrocardiograph device – deviations depending on age and gender

Characteristics of diastolic function of healthy subjects analyzed by microvoltage variability of isoelectric segments, recorded by three-axial high resolution electrocardiograph device – deviations depending on age and gender

Automatic detection of onset and offset of QRS complexes independent of isoelectric segments

Accurate location to onset and offset of QRS complex from ECG signal is help measuring other features and it is a important and challenge task to recognize these onsets and offsets from ECG signal without isoelectric segment. The algorithm, which is introduced in this paper, does not depend on isoelectric segment and can accurately detect these onsets and offsets. In the algorithm, for every sample within about a cardio cycle of locally normalized ECG signal, two fitting straight lines are obtained respectively, from two sets of samples before and after the sample. And then two gradients and a smaller included angle corresponding to the two fitted lines are calculated. Third, those samples whose two gradients satisfied a pre-set value are taken as candidates for the R peak, and the sample with the minimal included angle is regarded as the R peak in this cardiac cycle. Finally, respectively before and after the detected R peak, the algorithm researches the onset and the offset of the QRS complex according to the same decision strategy. All 32 sets of 12-lead ECG records from http://physionet.org/pn3/twadb/ are employed to evaluate the method. The experimental results show that compared with three traditional methods, the method can more accurately detect all onsets and offsets and has better robust on interference.